Imidacloprid represents the new generation of neurotoxic insecticides,
which exhibit more selective toxicity for insects relative to mammals.
Since being introduced in the insecticide market in 1992, the use of
imidacloprid has increased yearly. It ranked as one of the top selling
pesticides in the world in 2001-2002. For the most part, it is
replacing the acetylcholinesterase inhibitors, the organophosphorus
compounds and methylcarbamates.
Many organophosphates are potent neurotoxins, functioning by
inhibiting the action of acetylcholinesterase (AChE) in nerve cells.
They are one of the most common causes of poisoning worldwide, and are
frequently intentionally used in suicides in agricultural areas. Their
toxicity is not limited to the acute phase, however, and chronic
effects have long been noted. Neurotransmitters such as acetylcholine
(which is affected by organophosphate pesticides) are profoundly
important in the brain's development, and many OPs have neurotoxic
effects on developing organisms even from low levels of exposure.
examples:
* malathion
* diazinon
* phosmet (Imidan(R))
* chlorpyrifos (Lorsban(R))
Some of the organophosphates are very toxic. Parathion, for example,
is 30 times more toxic than DDT. Each year organophosphates poison
thousands of humans throughout the world, causing hundreds of deaths.
Medical personnel caring for poisoning victims are also at risk. They
may be seriously poisoned by the excretions of, and even the vapors
emanating from, their patients.
Carbamate insecticides are also inhibitors of acetylcholinesterase,
but their action is reversible.
Some examples:
* carbaryl (Sevin(R))
* aldicarb (Temik(R))
* methomyl (Lannate(R))
Features:
* These compounds are rapidly detoxified and excreted so their
risk to warm-blooded animals is less than the other agents we have
looked at.
* They are degraded rapidly in the environment so persistence is
not a problem.
* They are, however, a danger to many useful insects, especially honeybees.
--
Peter L. Borst
Danby, NY USA
42.35, -76.50
http://picasaweb.google.com/peterlborst
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